What is the use of question mark and colon (? and :) mean for in PHP?

[arvind vohra]

Please describe me what is the main use and difference between question mark and colon (? and :) in php ?

function get_all_state_details($state_id) 
 {
  $sql = "SELECT *  from  states  ";
  $rows = $this->db->query($sql);
  while ($record = $this->db->fetch_array($rows))
	{
   $strSelected = $record['state_id'] == $state_id ? 'selected = "selected"' : '';
   $strState .= '<option value = "'.$record['state_id'].'" '.$strSelected.' >'.$record['state_name'].'</option>';
   $i++;
  } 
  return $strState;
 }

[Rabbit]

It's an alternate form for if then else.

[Bharat383]

it's comparison operator same as if...else condition...